Sharp Inside Corner Problem

[rickh]

I am using VCarvePro, trying to get sharp inside corners on 4 x 7 photo frames. I am using a 130 degree bit that is 2.125 in diameter. For some reason the outside lines formed by the sharp inside corners do not line up with the outside lines of the straight sections. They jut out slightly. Any suggestions?

[Gary Campbell]

Rick...
Make sure that the bit geometry is exact. Search the forum for bit info. There are some posts that explain how to measure V & other bits.
Gary

[mzettl]

Rick, I just had the same problem with a 60 degree V. After a lot of fooling around, I came to the conclusion that the bit geometry was off, just as Gary suggests. Some searching on this forum ultimately led me to Paul Zank's V bit checking routine on the ShopBot Wiki. Here is the link:

http://shopbotwiki.com/index.php?title=CheckVBitAngle

His routine is designed for a 90 degree bit, but you can use it as a template and make a routine for any angle V that you wish to check. Worked for me, and I hope this helps.

Matt

[myxpykalix]

if you want to get tools that are exactly what they are supposed to be to eliminate that part of the problem, check out www.centuriontools.com (http://www.centuriontools.com)

[mzettl]

Jack makes a good point. I just got my first bits from Centurion, but have not yet used the 60 deg V. I planned on checking it sometime within the next few days.

There is one caveat, however. One of the things that Fred from Centurion explained at the Kitty Hawk Camp ShopBot was that the nature of bit manufacture resulted in a .25 spiral not being actually .25. Some material has to be removed from the .25 blank. The .25 down spiral that I received from Centurion is actually .245. Nonetheless, it is an excellent bit. I now measure all of my bits. In many applications, it may not make an appreciable difference, but I do a lot of joints in furniture construction on the Bot, and .005 can make a difference.

Brady Watson and others have made this point on this forum from time to time. Centurion does make extremely high quality bits at a reasonable price, and are willing to work with buyers, even small buyers, in making up bits for special needs. They will certainly get more of my business.